Improve process launch handle sharing API.

base/process/launch_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/process/launch.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sched.h>
@@ skipping 289 matching lines @@
                       const LaunchOptions& options) {
 #if defined(OS_MACOSX)
   if (FeatureList::IsEnabled(kMacLaunchProcessPosixSpawn)) {
     // TODO(rsesek): Do this unconditionally. There is one user for each of
     // these two options. https://crbug.com/179923.
     if (!options.pre_exec_delegate && options.current_directory.empty())
       return LaunchProcessPosixSpawn(argv, options);
   }
 #endif
 
-  size_t fd_shuffle_size = 0;
-  if (options.fds_to_remap) {
-    fd_shuffle_size = options.fds_to_remap->size();
-  }
-
   InjectiveMultimap fd_shuffle1;
   InjectiveMultimap fd_shuffle2;
-  fd_shuffle1.reserve(fd_shuffle_size);
-  fd_shuffle2.reserve(fd_shuffle_size);
+  fd_shuffle1.reserve(options.fds_to_remap.size());
+  fd_shuffle2.reserve(options.fds_to_remap.size());
 
   std::vector<char*> argv_cstr;
   argv_cstr.reserve(argv.size() + 1);
   for (const auto& arg : argv)
     argv_cstr.push_back(const_cast<char*>(arg.c_str()));
   argv_cstr.push_back(nullptr);
 
   std::unique_ptr<char* []> new_environ;
   char* const empty_environ = nullptr;
   char* const* old_environ = GetEnvironment();
@@ skipping 119 matching lines @@
         if (HANDLE_EINTR(
                 ioctl(options.ctrl_terminal_fd, TIOCSCTTY, nullptr)) == -1) {
           RAW_LOG(WARNING, "ioctl(TIOCSCTTY), ctrl terminal not set");
         }
       } else {
         RAW_LOG(WARNING, "setsid failed, ctrl terminal not set");
       }
     }
 #endif  // defined(OS_CHROMEOS)
 
-    if (options.fds_to_remap) {
-      // Cannot use STL iterators here, since debug iterators use locks.
-      for (size_t i = 0; i < options.fds_to_remap->size(); ++i) {
-        const FileHandleMappingVector::value_type& value =
-            (*options.fds_to_remap)[i];
-        fd_shuffle1.push_back(InjectionArc(value.first, value.second, false));
-        fd_shuffle2.push_back(InjectionArc(value.first, value.second, false));
-      }
+    // Cannot use STL iterators here, since debug iterators use locks.
+    for (size_t i = 0; i < options.fds_to_remap.size(); ++i) {
+      const FileHandleMappingVector::value_type& value =
+          options.fds_to_remap[i];
+      fd_shuffle1.push_back(InjectionArc(value.first, value.second, false));
+      fd_shuffle2.push_back(InjectionArc(value.first, value.second, false));
     }
 
     if (!options.environ.empty() || options.clear_environ)
       SetEnvironment(new_environ.get());
 
     // fd_shuffle1 is mutated by this call because it cannot malloc.
     if (!ShuffleFileDescriptors(&fd_shuffle1))
       _exit(127);
 
     CloseSuperfluousFds(fd_shuffle2);
@@ skipping 297 matching lines @@
   jmp_buf env;
   if (setjmp(env) == 0) {
     return CloneAndLongjmpInChild(flags, ptid, ctid, &env);
   }
 
   return 0;
 }
 #endif  // defined(OS_LINUX) || defined(OS_NACL_NONSFI)
 
 }  // namespace base